1. Field of the Invention
The present invention relates to data transfer through a communication system channel, and, more particularly, to transfer of data information with respect to a recording medium.
2. Description of the Related Art
Increasingly, consumer electronics applications require low-cost implementations for data storage, including associated read/write signal processing and servo-control electronics for a disc drive. Many applications require relatively modest data rates such as the 65 Kb/s data rate characteristic of MPEG audio. JPEG picture storage in digital cameras and low-rate MPEG video data storage are also low data rate applications. Cellular handsets, with their extreme cost sensitivity and emerging picture-handling and messaging capabilities, are another application. Speed requirements are modest, and host processors already incorporate hardware-assists for error correction and signal detection.
In magnetic and optical recording/playback disc drive systems, designers of the prior art have focused on high data-throughput and low access time as design goals while striving for a moderate cost. However, high data-throughput and low access time tend to require comparatively costly hardwired solutions. Hardwired solutions may include dedicated circuit designs to implement different functions of the disc drive system.
As integrated circuit (IC) semiconductor processes continue to allow for increased IC circuit density and higher processor operating (clock) speed, many circuit operations previously implemented with dedicated circuits might now be implemented with digital processing techniques. Signal processing as steps of a software program trades processor memory capacity and time-multiplexing complexity of processing activities for a reduction in the number of dedicated circuits. Software-based signal processing also allows flexibility when reconfiguring a system's operation to new design requirements or to remedy design flaws discovered during mass production without discarding existing system circuitry.
Therefore, it is desirable to provide a disc drive system for low data rate applications that implements many circuit operations, such as read signal detection and related servo functions, as digital signal processing steps in a dedicated processor